Question

Grace is comparing cell phone plans. A prepaid phone plan costs $0.20 per minute and has no monthly fee. A contracted phone plan costs $50 per month and $0.02 per minute. How will the graphs of the monthly costs of the two cell phone plans compare where x represents minutes purchased in a month?

The prepaid phone plan will have a steeper line and lower y-intercept.
The contracted phone plan will have the same steepness and a higher y-intercept.
The prepaid phone plan will have a less steep line and the same y-intercept.
The contracted phone plan will have a steeper line and same y-intercept.

Answer 1

The prepaid plan: y = 0.20x (slope 0.20, y-intercept 0).
The contracted plan: y = 0.02x + 50 (slope 0.02, y-intercept 50).

So the prepaid plan has the steeper line and the lower y-intercept.